Open channel flowmeters generally include a fluid velocity sensor and a liquid level sensor. The sensed velocity is converted to a mean velocity of the liquid flowing in a cross section of the pipe or conduit, and the level measurement provides an estimate of the cross sectional area through which the mean velocity flows. The volumetric flow rate is then computed as the product of cross sectional area and mean velocity.
Level sensors used in such flowmeters are generally piezoresistive pressure transducers which require substantial compensation to reduce errors in level measurements caused by temperature variations of the liquid. The present invention relates to a method and apparatus for compensating for temperature variations in the pressure transducer of an open channel flowmeter or in a flowmeter which measures only level and computes flow based on a known relationship such as the Manning equation.